C. de Weerth

Maternal prenatal stress and cortisol reactivity to stressors in human infants

Early life factors can shape the development of hypothalamic pituitary adrenal (HPA) axis. Maternal prenatal stress might constitute such an early environmental factor. As little is known about the relation between maternal prenatal stress and cortisol reactivity in human offspring, we performed a longitudinal study including four assessments of infant cortisol reactivity to stressful events in a non-clinical population. General and pregnancy-related feelings of stress and anxiety, as well as circadian cortisol levels, were measured in 173 mothers in the last trimester of pregnancy. Infant cortisol reactivity was measured at 5 weeks to a bathing session, at 8 weeks to a vaccination, at 5 months to a stressful mother–infant interaction (still face procedure), and at 12 months to a maternal separation (strange situation procedure). Maternal prenatal fear of bearing a handicapped child was a consistent predictor of infant cortisol reactivity. Although the effects were mild, higher fear was significantly related to higher salivary cortisol reactivity to the bathing session and to decreased cortisol reactivity to vaccination and maternal separation. Thus, pregnancy-specific anxieties predict infant cortisol reactivity in the first year of life, but the direction of the effect depends on infant age and/or the nature of the stressor. While this specific anxiety was a better predictor than stress experience or maternal cortisol concentrations, the underlying mechanisms of these associations remain unclear. Future studies should try to incorporate multiple measures of HPA-axis reactivity during development when studying the long-term consequences of maternal prenatal stress.

Cortisol reactions to a social evaluative paradigm in 5- and 6-year-old children

The goal of the present study was to develop a stress paradigm to elicit cortisol secretory responses in a group of 5- and 6-year-old children as a whole. To this end, we tested a paradigm containing elements of social evaluative threat, unpredictability and uncontrollability, and with a duration of 20 min. The Childrens Reactions to Evaluation Stress Test is composed of three short tasks that children have to perform in front of a judge. The tasks are rigged so as to provoke (partial) failure in the childs performance. Participants were 42 children (M = 68.0 months, SD = 4.3). Six saliva samples were taken during the testing session to obtain cortisol measurements of baseline concentrations, stress reactivity, and recovery. Our findings showed that this paradigm was effective in provoking a significant increase in salivary cortisol concentration in the group as a whole, with no effects of possible confounders (childs sex, age or school, parental educational level, time of testing, sex of experimenter, and sex of judge). The mean cortisol concentration increase for the group was 127.5% (SD = 190.9); 61% of the children could be classified as reactors (mean increase of 214%, SD = 201.5), and 39% as non-reactors (mean decrease of 7.8%, SD = 16.8). To our knowledge, this is the first study in this age group that shows a significant cortisol response for the group as a whole to a standardized laboratory paradigm. As such, this paradigm is a promising tool to be used in future research on early life interactions between physiology and psychology.

Cortisol levels of infants in center care across the first year of life: links with quality of care and infant temperament

Abstract Cortisol concentrations of older children in childcare centers have been found to be higher than at home. This study focuses on infant cortisol in childcare centers throughout the first year of life, and aims to investigate whether inter-individual differences can be explained by temperament, the quality of maternal behavior, and the quality of center care. Sixty-four infants were followed for 9 months after entering care at 3 months of age. Salivary samples were taken at 10.00 h and 16.00 h in center care (in post-entry weeks 1, 2, 3, 4, 8, 12, 16, 24, and 36) and at home (in post-entry weeks 1, 24, and 36). Prior to entry, mothers completed a temperament questionnaire and the quality of maternal behavior (sensitivity and cooperation) was observed during routine bathing sessions. Subsequently, the infants were visited three times at center care to observe the quality of infant’s interactive experiences with their professional caregiver. Longitudinal regression models showed that both morning and afternoon cortisol were higher in center care compared to home. Longitudinal regression models showed that infants receiving higher quality of maternal behavior displayed higher morning cortisol in center care, compared to infants receiving lower quality of maternal behavior. Higher quality of maternal behavior was also related to higher afternoon cortisol in center care, but only in infants high in negative emotionality. Center care quality was not related to cortisol. In sum, young infants show higher cortisol concentrations in center care that are related to infant temperament and quality of maternal behavior at home.

Stress in adults with congenital deafblindness and an intellectual disability: Information from their cortisol curves

Adults with congenital deafblindness and an intellectual disability are at high risk for exposure to chronic and severe stress. Sensory deprivation, separations from primary caregivers, and difficulties in communication, from birth on, make daily life stressful for them. Chronic and high stress can lead to deviancies in the cortisol curve. This, in turn, can have negative effects on mental and physical health. Nothing is known yet about the cortisol curve of adults with congenital deafblindness and an intellectual disability, but our hypothesis is that it will be deviant. In this study, the cortisol curve of six participants with congenital deafblindness was compared to the curve of 40 typical controls. Remarkably, in spite of all past and present stress factors, the cortisol curve of the participants was rather normal. Possible explanations for this finding are discussed, amongst others individual differences in experiencing stress. Implications for further research are discussed.

Acute psychosocial stress and children's memory

Abstract We investigated whether children’s performance on working memory (WM) and delayed retrieval (DR) tasks decreased after stress exposure, and how physiological stress responses related to performance under stress. About 158 children (83 girls; Mage = 10.61 years, SD = 0.52) performed two WM tasks (WM forward and WM backward) and a DR memory task first during a control condition, and 1 week later during a stress challenge. Salivary alpha-amylase (sAA) and cortisol were assessed during the challenge. Only WM backward performance declined over conditions. Correlations between physiological stress responses and performance within the stress challenge were present only for WM forward and DR. For WM forward, higher cortisol responses were related to better performance. For DR, there was an inverted U-shape relation between cortisol responses and performance, as well as a cortisol × sAA interaction, with concurrent high or low responses related to optimal performance. This emphasizes the importance of including curvilinear and interaction effects when relating physiology to memory.

Associations between circadian and stress response cortisol in children

Abstract Hypothalamic–pituitary–adrenal (HPA) axis functioning is characterized by the baseline production of cortisol following a circadian rhythm, as well as by the superimposed production of cortisol in response to a stressor. However, it is relatively unknown whether the basal cortisol circadian rhythm is associated with the cortisol stress response in children. Since alterations in cortisol stress responses have been associated with mental and physical health, this study investigated whether the cortisol circadian rhythm is associated with cortisol stress responses in 6-year-old children. To this end, 149 normally developing children (Mage = 6.09 years; 70 girls) participated in an innovative social evaluative stress test that effectively provoked increases in cortisol. To determine the cortisol stress response, six cortisol saliva samples were collected and two cortisol stress response indices were calculated: total stress cortisol and cortisol stress reactivity. To determine children’s cortisol circadian rhythm eight cortisol circadian samples were collected during two days. Total diurnal cortisol and diurnal cortisol decline scores were calculated as indices of the cortisol circadian rhythm. Hierarchical regression analyses indicated that higher total diurnal cortisol as well as a smaller diurnal cortisol decline, were both uniquely associated with higher total stress cortisol. No associations were found between the cortisol circadian rhythm indices and cortisol stress reactivity. Possible explanations for the patterns found are links with children’s self-regulatory capacities and parenting quality.

Does the arrival index predict physiological stress reactivity in children

Abstract Knowledge about childrens stress reactivity and its correlates is mostly based on one stress task, making it hard to assess the generalizability of the results. The development of an additional stress paradigm for children, that also limits stress exposure and test time, could greatly advance this field of research. Research in adults may provide a starting point for the development of such an additional stress paradigm, as changes in salivary cortisol and alpha-amylase (sAA) over a 1-h pre-stress period in the laboratory correlated strongly with subsequent reactivity to stress task (Balodis et al., 2010, Psychoneuroendocrinology 35:1363–73). The present study examined whether such strong correlations could be replicated in 9- to 11-year-old children. Cortisol and sAA samples were collected from 158 children (83 girls) during a 2.5-h visit to the laboratory. This visit included a 1-h pre-stress period in which children performed some non-stressful tasks and relaxed before taking part in a psychosocial stress task (TSST-C). A higher cortisol arrival index was significantly and weakly correlated with a higher AUCg but unrelated to cortisol reactivity to the stressor. A higher sAA arrival index was significantly and moderately related to lower stress reactivity and to a lower AUCi. Childrens personality and emotion regulation variables were unrelated to the cortisol and sAA arrival indices. The results of this study do not provide a basis for the development of an additional stress paradigm for children. Further replications in children and adults are needed to clarify the potential meaning of an arrival index.

Chapter 3 Impact of maternal prenatal psychosocial stress and maternal obesity on infant microbiota

The prenatal period is a critical window of development for all major physiological systems in the human body. During pregnancy, maternal prenatal psychosocial stress (PNS) and maternal obesity are identified as risk factors for infant and child health. Several possible mechanisms have been suggested to explain this link, including the transfer of maternal microbiota to offspring. PNS and maternal obesity may negatively affect maternal microbiota during pregnancy. By means of maternal microbial transfer in utero and at birth, PNS and maternal obesity could negatively affect the offsprings gut microbial colonisation. During delivery infants will come in contact with maternal vaginal and gut microbiota, and a spurt in infant gut colonisation will commence. Appropriate colonisation and gut microbiota development in new-borns are important for gut health, and therefore for child health and development. Results from animal and human studies show that PNS can affect the infant microbial composition. These findings need to be confirmed in large prospective cohort studies. In addition, a number of human studies indicate that maternal obesity may alter maternal gut microbiota and through vertical transfer of obesogenic maternal microbes may consequently predispose offspring to obesity. The relevance of these maternal obesogenic microbes in the infants gut for weight trajectory over the life course requires further evaluation. In this chapter, we will review the current understanding of how PNS and maternal pregnancy obesity may affect maternal gut microbiota and consequently infant microbiota and health. We will also discuss recent findings concerning proposed mechanisms of action. Finally, we will offer recommendations for clinical practice and future research.